1. Field of the Invention
The present invention relates to a switch apparatus suitable for an operation of an electric mirror or the like of a motor vehicle.
2. Description of the Related Art
There is known a switch apparatus for an electric mirror that an operation knob is mounted on a switch case so as to be rocked about in an optional direction relative to the switch case. In the known switch apparatus, for example, press points corresponding to each of upward, downward, right and left adjustment directions are provided at intervals of 90 degrees on a peripheral edge portion of the operation knob. When any one of press points is selectively pressed, a mirror tilting motor constituted by two motors for upward and downward adjustment and for right and left adjustment is rotated in a normal direction or in a reverse direction so as to adjust the tilt of the mirror. In addition, there is another apparatus that the press points are provided at intervals of 45 degrees to be adjustable also in the case of pressing the press points of diagonal positions.
Patent reference 1: Japanese utility model publication No. H05-5629.
Patent reference 2: Japanese patent No. 3,766,251.
The brief construction of the switch apparatus as described above is shown in FIG. 20 and FIG. 21. FIG. 20 is an exploded view of an essential part, in which four mounting legs 2 (see FIG. 21) project from an inside wall of a substantially square operation knob 1. The mounting legs 2 are fitted into a mounting hole 4 provided in the switch case 3, and hooks 2a provided on distal ends thereof are engaged with a flange 4b of a peripheral wall 4a provided in the periphery of the mounting hole 4, whereby the operation knob 1 is mounted on the mounting leg 2.
Between the operation knob land the mounting legs 2 there is interposed a rubber spring 5, and eight lift springs 5a are formed integrally at intervals of 45 degrees in a projecting fashion so as to lift and support the operation knob 1 in such a manner that each tip of the lift springs 5a supports the bottom of the peripheral portion of the operation knob 1. These supporting points correspond to press points P1˜P8 set substantially at intervals of 45 degrees on a peripheral edge of the operation knob 1. When any one of the press points is pressed, a total of three corresponding lift spring 5a and neighboring lift springs on both sides thereof are compressed and elastically deformed at the same time to tilt the operation knob 1, while, when releasing the press of the operation knob 1, the lift springs 5a return to the original state to restore the tilt of the operation knob 1 to the original state.
Actuator rods 6 are housed in the three lift springs among eight lift springs 5a and inserted at the lower ends thereof through bores 3a formed in an upper wall of the switch case 3, into the switch case 3 thereby abutting on inclined walls 7a of sliders 7. The sliders 7 are provided three correspondingly to the actuator rods 6 and each have movable contacts 8. The sliders 7 are slidable on a circuit board 9 in opposition to return springs 7b. When the slider 7 moves in opposition to the return spring 7b by pressing down the actuator rod 6, the movable contact 8 comes into contact with a fixing contact 9a on the circuit board 9 so as to turn the switch on. When releasing the pressing of the actuator rod 6, the slider 7 is returned to the original position by the return spring 7b so as to turn the switch off.
A switch element is comprised of the actuator rod 6, the slider 7, the movable contact 8, the return spring 7b and the fixed contact 9a. The normal and reverse rotation of the upward and downward adjustment motor and the normal and reverse rotation of the right and left adjustment motor are capable of being controlled by the combination of a switching-on operation and a switching-off operation of three switch elements. Only three switch elements are sufficient for eight lift springs 5a whereby it is possible to reduce the number of the switch element relative to the lift spring 5a. 
FIG. 21 is a schematic view of an operation state of the operation knob 1. FIG. 21-A is a neutral state, FIG. 21-B is a pressing state of the operation knob 1 still in progress, and FIG. 21-C is a sufficiently pressed state. As shown in the phantom line in FIG. 21-A, when the center of the operation knob 1 is pressed, the whole operation knob 1 goes downward, so that all the switch elements are turned on to keep the neutral state. When one of the press points (P7 in this embodiment) is pressed, the mounting leg 2 close to this press point, as shown in FIG. 21-B, projects downward, and the operation knob 1 is tilted to the press point P7 by using the engaging portion between the mounting leg 2 on the opposite side thereof and the switch case 3 as a fulcrum, Then, the lift spring 5a is pressed by the neighboring portion of the press point P7. When completely pressed, the operation knob 1 comes to the state shown in FIG. 21-C. At this time, as shown in FIG. 21-C, the mounting leg 2 on the side of the fulcrum is slightly moved downward, depending upon the pressing condition.
In the conventional switch construction as above, the operation knob 1, when being pressed, moves in the upward and downward direction relative to the switch case 3. That is the same when the operation knob 1 is rocked. Accordingly, there is a possibility that a fluffy unsteady feeling is created in the operation of the operation knob 1, and there are cases that a more positively controlled steady operation is desired rather than an operation of the fluffy unsteady feeling, whereby the construction realizing the desire is required.
Further, as shown in FIG. 20, when any one of the press points P1˜P8 corresponding to eight lift springs 5a is pressed, the lift spring corresponding to the pressed press point and neighboring two lift springs are pressed at the same time. Then, if three switch elements are provided for P4, P6 and P8, and when any of these press points other than the press point 2 is pressed, any of the switch elements is switched to have the mirror adjustment motor operated in response thereto. However, when the press point P2 is pressed, none of the switch elements are arranged correspondingly to the press points P1˜P3, so that the mirror adjustment motor is not operated in response thereto. Therefore, since there is a possibility of being recognized as a malfunction in case of no response to the operation of the operation knob 1, it is also required to solve such situation as above. The present invention is intended to solve such problems.